1. Field of the Invention
The invention relates to optical fibre drop cables for use in telecommunications systems and particularly, but not exclusively, to such cables for use in connecting between a customer's premises and a connection point common to a number of such customers.
2. Description of the Related Art
In the field of telecommunications networks, typically cables run from an exchange to a cabinet mounted at street level and from this cabinet cables are led to a customer's premises, usually by way of an aerial, or suspension installation comprising a cable suspended in catenary from poles or surrounding buildings. These aerially suspended cables leading to the customer premises are known as the final drop wire.
Historically a final drop wire has typically comprised a number of insulated conducting wires contained in a sheath. More recently the development of optical fibers has made it desirable to replace the conducting wires in drop wires with optical fibers, since the latter can transmit significantly more data. However, it is also desirable that the drop wire should carry an electrical supply in order that a telephone connected to the drop wire can be used in emergency situations when the mains electrical supply to the premises in which the telephone is located has been interrupted. For this reason, it is desirable for a drop wire to include one or more optical fibers and a pair of insulated copper conductor wires.
The applicant's application GB-A-2270992 discloses a cable containing separable electrical conductors and optical fibers. The cable comprises electrical power conductors for conveying mains voltage electrical supplies, a plurality of optical fibers and sheathing for the conductors and fibers. The sheathing is in the form of a figure of eight and defines two separate chambers; one for the electrical conductors and the other for the optical fibers. However, this cable is intended for underground routing and not for suspension installation. Furthermore, it is not suitable for conducting a relatively low voltage electrical supply for powering a telephone or otherwise as a final drop wire.